So, you can add whole shells to your garden bed or compost pile, but they will break down slowly. If you want them to break down faster, put them in a bag and take a hammer to them, THEN add them to your compost or garden.

Are scallop shells good for the garden?

If you are an avid gardener, you may want to consider using your discarded shells directly in your yard. The calcium they contain turns out to be great fertilizer. For instance, they can be directly added to your compost to help lower soil acidity.

Can sea shells go in compost?

But just because it will eventually break down, does that mean you should compost it? Shellfish shells can be composted but will break down very slowly unless they are crushed into smaller pieces or ground into a meal.